Updated at 3:20 p.m. ET
VIENNA - Satellite surveillance has shown an increase in activity at an Iranian site suspected of links to alleged secret work on nuclear weapons, officials tell The Associated Press.
The reports come as the International Atomic Energy Agency and nations tracking Iran's nuclear program increase efforts to monitor such sites following the strongest IAEA report to date on alleged Iranian research and development of such weapons. But the significance is unclear.
One official cited intelligence from his home country, saying it appeared Tehran is trying to cover its tracks by sanitizing the site and removing any evidence of nuclear research and development. But two others reserved judgment while confirming sightings of increased activity. And in Washington, Pentagon spokesman Capt. John Kirby said he has "seen nothing to indicate that those concerns are warranted."
The focus is on a structure believed to be housing a large metal chamber at a military site that a Nov. 8 International Atomic Energy Agency report described as being used for nuclear-related explosives testing.
The official with the most precise information said satellite imagery of the site, at Parchin, southwest of Tehran, shows increased activity, including an unusual number of vehicles arriving and leaving. He described the movements, recorded Nov. 4-5, as unusual and said his country views it as evidence that Iran is trying to "clean" the area of traces of weapons-related work
"Freight trucks, special haulage vehicles and cranes were seen entering and leaving ... (and) some equipment and dangerous materials were removed from the site," said a summary he provided to the AP.
Counterparts from two other countries agreed there had been more activity than usual at the site around that date but could not conclude that pointed to an attempted cover-up by the Iranians.
The IAEA was alerted to the suspicions late last week, and a senior diplomat familiar with the issue said the agency was closely monitoring all suspect sites mentioned in the agency's report. He, like the officials, asked for anonymity because his information was confidential.
The IAEA said it would have no comment.
Ali Asghar Soltanieh, Iran's chief delegate to the IAEA, dismissed the reports as "childish stories." He told the AP he had not heard of any such activity, describing the claims as "ridiculous."
Iran is already under U.N. Security Council sanctions because of concerns it seeks to develop nuclear weapons, and the IAEA report has increased international pressure. But the Islamic Republic insists it has no such intentions and says Israel, and its undeclared nuclear arsenal, is the main threat to the Middle East.
Reflecting its defiance, Iran was boycotting an IAEA meeting Monday attended by Israel and all Arab nations meant to explore the possibilities of establishing a nuclear-arms-free Mideast based on the experiences of other world regions with such zones.
In Washington, U.S. officials said the Obama administration will hit the Iranian economy with new sanctions Monday, teaming up with Britain and Canada in an effort to pressure Tehran to halt its suspected nuclear weapons program. The British announced the first measures, declaring they would cut off all financial ties with Iranian banks to stem the flow of funds for its nuclear and ballistic missile programs.
The coordinated actions by the United States and its two close allies represent the first direct response to the U.N. nuclear agency's recent report.
Iran's large Parchin complex is used for research, development, and production of ammunition, missiles, and high explosives. IAEA experts had already visited the site twice in 2005 and were allowed to pick several buildings at random for inspections that revealed nothing suspicious. But a former inspector who was part of that inspection told the AP that the site was too vast to be able to draw conclusions on the basis of such restricted and haphazard visits.
Iran asserts it is interested only in producing energy. But it has refused for over three years to allow the IAEA to probe growing suspicions that it is conducting research and development of such weapons and continuing to enrich uranium, which can be used both to power reactors of arm nuclear warheads.
Summarizing such fears in a Nov. 8 report that first mentioned the steel chamber believed to be used for nuclear testing, the agency said some of the alleged activities it listed could have no other purpose than to make the bomb.
Ahead of that report, on Oct. 30, Iran invited top IAEA investigator Herman Nackaerts to Tehran for talks "aiming at a resolution of matters." That would have given Nackaerts a chance to ask for a renewed trip to Parchin that included a visit to the suspected building.
However, on Friday Soltanieh, the Iranian delegate, abruptly announced that the trip was postponed, if not canceled. He blamed the IAEA, saying it had "messed up" the trip by publishing its report.
The decision could give Iran time to clean up sites mentioned in the report as being part of the secret work, should it chose to do so.